Development and Investigation of Energy Management System in Shipboard Power System under Different Ship Conditions
The need for energy conservation and reduction of fossil fuel consumption has resulted in the introduction of renewable energy sources in ships and hence the concept of green shipping concept has emerged. A marine microgrid integrated with renewables acts as a hybrid microgrid system. In this work, a solar photovoltaic system connected in the marine ship in addition to diesel generators to reduce fuel consumption thereby minimizing carbon emission. The Li battery is used as the energy storage system to control any abundance or shortage of power considering the State of Charge of the battery in the battery management system. A bidirectional DC/DC converter is used to interface the PV system with the battery energy storage system. The energy management system is implemented for the optimal power scheduling of various energy sources to reduce the usage of diesel generators. The integration of renewable energy sources into the microgrid often results in the instability of voltage and frequency, hence voltage and frequency controllers are developed in the proposed work to maintain within the limits. The entire marine ship system is designed considering the mathematical model of the solar PV system, battery, diesel generator, electric loads and propeller loads in MATLAB/Simulink 2018a version platform. In this work, the proposed energy management system along with controllers is studied under different ship conditions namely, regular cruising, full speed cruising, loading/unloading, harboring and docking. The battery management system inside the overall energy system ensures proper charge and discharge of the battery considering the SoC of the battery which leads to the extended life of the battery which is highly essential in islanded marine microgrids. Besides, the voltage and frequency of the marine system are well regulated by the V/f control algorithm maintaining the stability of the system. The ship is also modeled and simulated in HOMER-PRO software to calculate the fuel consumption, carbon emissions, and annualized cost under the same different ship conditions. The simulation results show that the proposed model with the energy management system and suitable controllers is effective under all ship conditions and produces promising results.